As a Borg drone he was capable of visiting Unimatrix Zero, and assisted in their fight for freedom in 2377. When Axum, leader of the Unimatrix Zero drones, asked Seven of Nine for help, Korok at first was opposed to bringing in outsiders. Nevertheless, their joint effort proved successful as Korok took over a Borg sphere and along with USS Voyager attacked Tactical Cube 138, the vessel that Janeway, Tuvok and Torres had infiltrated to deploy a nanovirus. The Voyager crew saw to it that the realm's occupants would retain their memories, and thus their individuality while awake as drones.
Following the incident, Korok was contacted by another Borg vessel under the control of former drones and they formed an alliance leading to a resistance movement against the Collective. (VOY: "Unimatrix Zero", "Unimatrix Zero, Part II")